Imaging lens

ABSTRACT

An imaging lens which forms an image of an object on a solid-state image sensor includes a first through fifth lens in order from an object side to an image side of the imaging lens. The imaging lens includes: a first lens that is a meniscus lens having a convex surface facing the object side; a second lens; and a third lens that is a meniscus lens and has a convex surface facing the image side near an optical axis of the imaging lens. The imaging lens further includes: a fourth lens having a concave surface facing the object side and a convex surface facing the image side near the optical axis; and a fifth lens. An F-value of the imaging lens is 2.5 or less.

The present application is based on and claims priority of Japanesepatent application No. 2014-138746 filed on Jul. 4, 2014, the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to imaging lenses which form an image ofan object on a solid-state image sensor such as a CCD sensor or a C-MOSsensor used in a compact image pickup device, and more particularly toimaging lenses which are built in image pickup devices mounted inincreasingly compact and low-profile smart phones and mobile phones,PDAs (Personal Digital Assistants), game consoles, information terminalssuch as PCs, and home appliances with a camera function.

Description of the Related Art

In recent years, there has been a general tendency that many informationterminals have a camera function. Also, home appliances with a camerafunction have been introduced into the market. For example, a user whois away from home can see in real time what is going on at home, throughthe camera mounted in a home appliance by telecommunication between thehome appliance and his/her smart phone. It is thought that productswhich enhance consumer convenience by adding a camera function to aninformation terminal or home appliance will be increasingly developed inthe future. The camera mounted in such a product is expected not only toprovide high resolution to cope with an increase in the number of pixelsbut also to be compact and low-profile and offer high brightness and awide field of view. Particularly, the imaging lens to be built in amobile terminal is strongly expected not only to be low-profile enoughto be applicable to a low-profile product but also to deliver highimaging performance.

However, in order to provide a low-profile imaging lens with a widefield of view and high brightness as described above, the followingproblem has to be addressed: it is difficult to correct aberrations inthe peripheral area of the image and ensure high imaging performancethroughout the image.

In the related art, for example, the imaging lens described inJP-A-2011-085733 (Patent Document 1) is known as a compacthigh-resolution imaging lens.

Patent Document 1 discloses an imaging lens which includes, in orderfrom an object side, a first lens group including a first lens having aconvex surface on the object side, a second lens group including asecond lens having a concave surface on an image side, a third lensgroup including a meniscus third lens having a concave surface on theobject side, a fourth lens group including a meniscus fourth lens havinga concave surface on the object side, and a fifth lens group including ameniscus fifth lens having an aspheric surface with an inflection pointon the object side. This configuration is intended to provide a compactimaging lens system which offers high resolution.

The imaging lens described in Patent Document 1 has a total track lengthof about 6.0 mm and the ratio of total track length to the diagonallength of the effective imaging plane of the image sensor (hereinafterreferred to as the “total length to diagonal ratio”) is about 0.9,offering a lens system which is relatively low-profile and correctsaberrations properly. However, its F-value is about 2.8, so itsbrightness is not sufficient. Furthermore, its field of view is about 65degrees, which is insufficient to meet the demand for a wide field ofview. Furthermore, in order for this configuration to offer an F-valueof 2.5 or less and a field of view of 70 degrees or more, the problemwith difficulty in correction of aberrations in the peripheral area ofthe image must be addressed.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problem, and anobject thereof is to provide a compact high-resolution imaging lenswhich meets the demand for low-profileness and offers high brightnesswith an F-value of 2.5 or less and a wide field of view and correctsvarious aberrations properly.

Here, “low-profile” implies that the total length to diagonal ratio ismuch smaller than 1.0 and “wide field of view” implies that the imagingfield of view is 70 degrees or more. In determination of the totallength to diagonal ratio, the diagonal length of the effective imagingplane of the image sensor is taken as equal to the diameter of aneffective imaging circle whose radius is the vertical height from anoptical axis to the point where a light ray incident on the imaging lensat a maximum field of view enters the image plane, namely the maximumimage height.

In the present invention, in terms of lens surface shape, a convexsurface or a concave surface means that the paraxial portion of thesurface (portion near the optical axis) is convex or concave. A“pole-change point” on an aspheric surface means a point on an asphericsurface at which a tangential plane intersects the optical axisperpendicularly. The values of total track length and back focus aredefined as distances on the optical axis as calculated with an opticalelement such as an IR cut filter or a cover glass removed.

According to one aspect of the present invention, there is provided animaging lens which forms an image of an object on a solid-state imagesensor, in which elements are arranged in the following order from anobject side to an image side: a first lens with positive refractivepower having a convex surface on the object side; a second lens withnegative refractive power having a concave surface on the image side; athird lens with negative refractive power; a fourth lens with negativerefractive power as a meniscus double-sided aspheric lens having aconvex surface on the image side; and a fifth lens as a double-sidedaspheric lens having a concave surface on the image side. The asphericimage-side surface of the fifth lens has a pole-change point off anoptical axis and the imaging lens satisfies conditional expressions (1)and (2) below:TTL/2ih≤0.8  (1)20<νd1−νd2<50  (2)

where

-   -   νd1: Abbe number of the first lens at d-ray    -   νd2: Abbe number of the second lens at d-ray    -   ih: maximum image height    -   TTL: total track length.

The imaging lens with the above configuration is composed of fiveconstituent lenses in which positive, negative, negative, negative, andpositive or negative refractive power constituent lenses are arranged inorder from the object side. The composite focal length of the second,third, fourth, and fifth lenses is negative refractive power, therebyenhancing the telephoto capability, and refractive power isappropriately distributed to the constituent lenses to make the imaginglens low-profile.

The first lens is a lens with positive refractive power having a convexsurface on the object side and its refractive power is strong enough toensure that the imaging lens is low-profile and offers a wide field ofview. The second lens is a lens with negative refractive power having aconcave surface on the image side and properly corrects sphericalaberrations and chromatic aberrations which occur on the first lens. Thethird lens has relatively weak negative refractive power among theconstituent lenses of the imaging lens and suppresses sphericalaberrations which occur on the first lens and the second lens. It isdesirable for the third lens to have an appropriate aspheric surface oneach side and if it has appropriate aspheric surfaces, high-orderspherical aberrations and coma aberrations can be made small. The fourthlens is a meniscus double-sided aspheric lens with negative refractivepower having a convex surface on the image side so that it not onlycontrols the angles of incident rays and corrects astigmatism but alsocontrols the angle of a chief ray incident on the image sensor andcorrects field curvature and distortion. The fifth lens is adouble-sided aspheric lens having a concave surface on the image sideand its aspheric image-side surface has a pole-change point to correctfield curvature and distortion and control the angle of a chief rayincident on the image sensor.

The conditional expression (1) defines an appropriate range for thetotal length to diagonal ratio. When the value is below the upper limitof the conditional expression (1), the imaging lens can meet the recentdemand for low-profileness.

The conditional expression (2) defines an appropriate range for thedifference between the Abbe numbers of the first lens and the secondlens at d-ray, and indicates a condition to properly correct chromaticaberrations which occur on the first lens. When materials which satisfythe conditional expression (2) are combined, chromatic aberrations canbe corrected properly.

Preferably, the imaging lens according to the present inventionsatisfies a conditional expression (3) below:0<νd3−νd4<40  (3)

where

-   -   νd3: Abbe number of the third lens at d-ray    -   νd4: Abbe number of the fourth lens at d-ray.

The conditional expression (3) defines an appropriate range for thedifference between the Abbe numbers of the third lens and fourth lens atd-ray. When material which satisfies the conditional expression (3) isused for the third and the fourth lenses, chromatic aberrations can becorrected properly even with a small F-value.

Preferably, the imaging lens according to the present inventionsatisfies conditional expressions (4) and (5):0.4<f1/f<1.0  (4)−1.5<f2345/f<−0.6  (5)

where

-   -   f: focal length of the overall optical system of the imaging        lens    -   f1: focal length of the first lens    -   f2345: composite focal length of the second, third, fourth and        fifth lenses.

The conditional expression (4) defines an appropriate range for theratio of the focal length of the first lens to the focal length of theoverall optical system, and indicates a condition to suppress sphericalaberrations, ensure low-profileness and offer a wide field of view. Ifthe value is above the upper limit of the conditional expression (4),the positive refractive power of the first lens would be too weak toensure that the imaging lens is low-profile and offers a wide field ofview, though it would be advantageous in suppressing sphericalaberrations. On the other hand, if the value is below the lower limit ofthe conditional expression (4), the positive refractive power of thefirst lens would be too strong and spherical aberrations would increase,though it would be advantageous in ensuring that the imaging lens islow-profile and offers a wide field of view.

The conditional expression (5) defines an appropriate range for theratio of the composite focal length of the second, third, fourth, andfifth lenses to the focal length of the overall optical system, andindicates a condition to correct chromatic aberrations properly. If thevalue is above the upper limit of the conditional expression (5), thenegative composite refractive power of the second, third, fourth, andfifth lenses would be too strong to shorten the total track length ofthe optical system. On the other hand, if the value is below the lowerlimit of the conditional expression (5), the negative compositerefractive power of the second, third, fourth, and fifth lenses would betoo weak to correct chromatic aberrations. When the conditionalexpression (5) is satisfied, aberrations can be corrected and the totaltrack length can be short.

Preferably, the imaging lens according to the present inventionsatisfies a conditional expression (6) below:1.5<r4/f<2.3  (6)

where

-   -   f: focal length of the overall optical system of the imaging        lens    -   r4: curvature radius of the image-side surface of the second        lens.

The conditional expression (6) defines an appropriate range for theratio of the curvature radius of the image-side surface of the secondlens to the focal length of the overall optical system of the imaginglens. If the value is above the upper limit of the conditionalexpression (6), the negative refractive power of the second lens wouldbe too weak to correct axial chromatic aberrations which occur on thefirst lens. On the other hand, if the value is below the lower limit ofthe conditional expression (6), the incidence angles of peripheral rayson the image-side surface of the second lens would be too large tosuppress coma aberrations. If the incidence angles of rays are toolarge, manufacturing error sensitivity would increase, making stablemass production difficult.

Preferably, the imaging lens according to the present inventionsatisfies a conditional expression (7) below:−1.9<(r1+r2)/(r1−r2)<−0.7  (7)

where

-   -   r1: curvature radius of the object-side surface of the first        lens    -   r2: curvature radius of the image-side surface of the first        lens.

The conditional expression (7) defines an appropriate range for theratio of the sum of the curvature radii of the object-side andimage-side surfaces of the first lens to the difference between them,namely the relation in curvature radius between the object-side andimage-side surfaces of the first lens, and indicates a condition to keepdistortion, astigmatism, and spherical aberrations within appropriateranges. If the value is above the upper limit of the conditionalexpression (7), the principal point of the first lens would shift towardthe image side, making it difficult to keep the total length of theimaging lens short. If the value is below the lower limit of theconditional expression (7), it would be difficult to correct sphericalaberrations.

Preferably, the imaging lens according to the present inventionsatisfies a conditional expression (8):−6.0<f45/f<−3.0  (8)

where

-   -   f: focal length of the overall optical system of the imaging        lens    -   f45: composite focal length of the fourth and fifth lenses.

The conditional expression (8) defines an appropriate range for theratio of the composite focal length of the fourth and fifth lenses tothe focal length of the overall optical system of the imaging lens, andindicates a condition to make the imaging lens low-profile, ensure anappropriate back focus, and correct chromatic aberrations properly. Ifthe value is above the upper limit of the conditional expression (8),the negative composite refractive power of the fourth and fifth lenseswould be stronger and undesirably the total track length would belonger, though it would be easy to ensure an appropriate back focus. Onthe other hand, if the value is below the lower limit of the conditionalexpression (8), the negative composite refractive power of the fourthand fifth lenses would be too weak to correct chromatic aberrationsproperly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing the general configuration of animaging lens in Example 1;

FIG. 2 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 1;

FIG. 3 is a schematic view showing the general configuration of animaging lens in Example 2;

FIG. 4 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 2;

FIG. 5 is a schematic view showing the general configuration of animaging lens in Example 3;

FIG. 6 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 3;

FIG. 7 is a schematic view showing the general configuration of animaging lens in Example 4;

FIG. 8 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 4;

FIG. 9 is a schematic view showing the general configuration of animaging lens in Example 5;

FIG. 10 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 5;

FIG. 11 is a schematic view showing the general configuration of animaging lens in Example 6;

FIG. 12 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 6;

FIG. 13 is a schematic view showing the general configuration of animaging lens in Example 7;

FIG. 14 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 7;

FIG. 15 is a schematic view showing the general configuration of animaging lens in Example 8;

FIG. 16 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 8;

FIG. 17 is a schematic view showing the general configuration of animaging lens in Example 9;

FIG. 18 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 9;

FIG. 19 is a schematic view showing the general configuration of animaging lens in Example 10; and

FIG. 20 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the preferred embodiment of the present invention will bedescribed in detail referring to the accompanying drawings. FIGS. 1, 3,5, 7, 9, 11, 13, 15, 17, and 19 are schematic views showing the generalconfigurations of the imaging lenses in Examples 1 to 10 according tothis embodiment, respectively. Since all these examples have the samebasic lens configuration, the general configuration of an imaging lensaccording to this embodiment is explained below referring to theschematic view of Example 1.

As shown in FIG. 1, the imaging lens according to this embodiment formsan image of an object on a solid-state image sensor and includes, inorder from an object side to an image side, an aperture stop ST, a firstlens L1 with positive refractive power having a convex surface on theobject side, a second lens L2 with negative refractive power having aconcave surface on the image side, a third lens L3 with negativerefractive power, a fourth lens L4 with negative refractive power as ameniscus double-sided aspheric lens having a convex surface on the imageside, and a fifth lens L5 as a double-sided aspheric lens having aconcave surface on the image side. The aspheric image-side surface ofthe fifth lens L5 has a pole-change point off an optical axis X. Afilter IR such as an infrared cut filter is located between the fifthlens L5 and an image plane IM. The filter IR is omissible.

In the imaging lens according to this embodiment, positive, negative,negative, negative, and negative power constituent lenses are arrangedin order from the object side. The four lenses other than the first lensL1 have negative refractive power to enhance the telephoto capability,and refractive power is appropriately distributed to the constituentlenses to make the imaging lens low-profile. However, as for the fifthlens L5, it may have weak positive refractive power, provided that thecomposite refractive power of the four lenses, namely the second lens L2to fifth lens L5, is negative. In Examples 5 to 10 shown in FIGS. 9 to20, the fifth lens L5 has positive refractive power.

The first lens L1 has a biconvex shape and suppresses sphericalaberrations and gives the required positive refractive power to theoverall optical system of the imaging lens. The shape of the first lensL1 is not limited to a biconvex shape. For example, it may be a meniscuslens having a convex surface on the object side as in Examples 2, 4, 6,7, 8, and 10 shown in FIGS. 3, 7, 11, 13, 15, and 19, respectively. Thecurvature radius of the object-side surface is smaller than thecurvature radius of the image-side surface so that the relation incurvature radius between them is appropriate to suppress sphericalaberrations.

The second lens L2 has a biconcave shape and properly corrects sphericalaberrations, coma aberrations, and chromatic aberrations which occur onthe first lens L1. The shape of the second lens L2 is not limited to abiconcave shape. For example, it may be a meniscus lens having a concavesurface on the image side as in Examples 8 and 10 shown in FIGS. 15 and19, respectively.

The third lens L3 has a meniscus shape with a convex surface on theobject side and its negative refractive power is relatively weak amongthe constituent lenses of the imaging lens. The both surfaces of thethird lens L3 are aspheric and used to properly correct sphericalaberrations, coma aberrations and field curvature which occur on thefirst lens L1 and the second lens L2. The third lens L3 should havenegative refractive power but it may be a biconcave lens as in Example 4shown in FIG. 7 or a meniscus lens having the concave surface on theobject side as in Examples 2, 3, 6, 8, and 9 shown in FIGS. 3, 5, 11,15, and 17, respectively.

The fourth lens L4 has a meniscus shape with a convex surface on theimage side and the aspheric surfaces on the both sides are used not onlyto control the angle of rays incident on the fourth lens L4 and correctastigmatism, but also to control the angle of a chief ray incident onthe image sensor and correct field curvature and distortion.

The fifth lens L5 has a meniscus shape with a convex surface on theobject side, its concave image-side surface ensures an appropriate backfocus, and enhances the telephoto capability. The aspheric surfaces onthe both sides are used to properly correct spherical aberrations andfield curvature which occur on the fourth lens L4. The asphericimage-side surface has a pole-change point off the optical axis X tocontrol the angles of peripheral rays incident on the image plane IMappropriately.

In the imaging lens according to this embodiment, all the constituentlenses are made of plastic material, so the manufacturing process ismade easier and the imaging lens can be mass-produced at low cost. Allthe lens surfaces have appropriate aspheric shapes so that variousaberrations can be corrected more properly.

When the imaging lens according to this embodiment satisfies conditionalexpressions (1) to (8) below, it brings about advantageous effects:TTL/2ih≤0.8  (1)20<νd1−νd2<50  (2)0<νd3−νd4<40  (3)0.4<f1/f<1.0  (4)−1.5<f2345/f<−0.6  (5)1.5<r4/f<2.3  (6)−1.9<(r1+r2)/(r1−r2)<−0.7  (7)−6.0<f45/f<−3.0  (8)

where

-   -   f: focal length of the overall optical system of the imaging        lens    -   f1: focal length of the first lens L1    -   f2345: composite focal length of the second lens L2, the third        lens L3, the fourth lens L4 and the fifth lens L5    -   f45: composite focal length of the fourth lens L4 and the fifth        lens L5    -   r1: curvature radius of the object-side surface of the first        lens L1    -   r2: curvature radius of the image-side surface of the first lens        L1    -   r4: curvature radius of the image-side surface of the second        lens L2    -   νd1: Abbe number of the first lens L1 at d-ray    -   νd2: Abbe number of the second lens L2 at d-ray    -   νd3: Abbe number of the third lens L3 at d-ray    -   νd4: Abbe number of the fourth lens L4 at d-ray    -   TLA: total track length    -   ih: maximum image height.

When the imaging lens according to this embodiment satisfies conditionalexpressions (1a) to (8a) below, it brings about more advantageouseffects:0.5<TTL/2ih<0.8  (1a)25<νd1−νd2<40  (2a)0<νd3−νd4<38  (3a)0.5<f1/f<0.9  (4a)−1.5<f2345/f<−0.7  (5a)1.5<r4/f<2.0  (6a)−1.7<(r1+r2)/(r1−r2)<−0.7  (7a)−5.0<f45/f<−3.0.  (8a)

In the above conditional expressions, the signs have the same meaningsas in the preceding paragraph.

When the imaging lens according to this embodiment satisfies conditionalexpressions (1b) to (8b) below, it brings about particularlyadvantageous effects:0.67≤TTL/2ih≤0.75  (1b)28<νd1−νd2<35  (2b)0<νd3−νd4<35  (3b)0.6≤f1/f≤0.8  (4b)−1.42≤f2345/f≤−0.76  (5b)1.65≤r4/f≤1.9  (6b)−1.55≤(r1+r2)/(r1−r2)≤−0.86  (7b)−4.68≤f45/f≤−3.49.  (8b)

In the above conditional expressions, the signs have the same meaningsas in the paragraph before the preceding paragraph.

In this embodiment, all the lens surfaces are aspheric. The asphericshapes of these lens surfaces are expressed by Equation 1, where Zdenotes an axis in the optical axis direction, H denotes a heightperpendicular to the optical axis, k denotes a conic constant, and A4,A6, A8, A10, A12, A14, and A16 denote aspheric surface coefficients.

$\begin{matrix}{Z = {\frac{\frac{H^{2}}{R}}{1 + \sqrt{1 - {\left( {k + 1} \right)\frac{H^{2}}{R^{2}}}}} + {A_{4}H^{4}} + {A_{6}H^{6}} + {A_{8}H^{8}} + {A_{10}H^{10}} + {A_{12}H^{12}} + {A_{14}H^{14}} + {A_{16}H^{16}}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Next, examples of the imaging lens according to this embodiment will beexplained. In each example, f denotes the focal length of the overalloptical system of the imaging lens, Fno denotes an F-number, ω denotes ahalf field of view, TTL denotes total track length, ih denotes a maximumimage height. i denotes a surface number counted from the object side, rdenotes a curvature radius, d denotes the distance on the optical axisbetween lens surfaces (surface distance), Nd denotes a refractive indexat d-ray (reference wavelength), and νd denotes an Abbe number at d-ray.As for aspheric surfaces, an asterisk (*) after surface number iindicates that the surface concerned is an aspheric surface.

Example 1

The basic lens data of Example 1 is shown in Table 1 below.

TABLE 1 Example 1 in mm f = 2.917 Fno = 2.45 ω(°) = 37.6 TTL = 3.25 ih =2.30 Surface Data Curvature Surface Refractive Abbe Surface No. i Radiusr Distance d Index Nd Number νd (Object Surface) Infinity Infinity 1(Stop) Infinity −0.170 2* 1.022 0.441 1.544 55.57 3* −13.146 0.048 4*−4.287 0.234 1.639 23.25 5* 4.858 0.284 6* 42.666 0.267 1.535 55.66 7*18.737 0.276 8* −2.087 0.301 1.639 23.25 9* −2.715 0.060 10*  1.1250.512 1.535 55.66 11*  0.916 0.400 12  Infinity 0.175 1.517 64.17 13 Infinity 0.314 Image Plane Infinity Lens Start Surface Focal LengthConstituent Lens Data 1 2 1.762 2 4 −3.528 3 6 −62.711 4 8 −17.384 5 10−61.956 Composite Focal Length f2345 −2.210 f45  −11.651 AsphericSurface Data 2nd Surface 3rd Surface 4th Surface 5th Surface 6th Surfacek −6.114E−02 −4.101E+01 −1.300E+02  4.489E+01 −1.315E−01 A4 −6.219E−02−7.195E−04 1.036E−01 2.320E−01 −3.038E−01 A6  2.299E−01 −1.983E+00−1.063E+00  7.439E−01  5.806E−02 A8 −1.989E+00  1.225E+01 1.113E+01−2.971E+00  −1.054E+01 A10  3.816E+00 −4.177E+01 −4.128E+01  1.313E+01 7.809E+01 A12 −4.291E+00  6.014E+01 6.352E+01 −3.130E+01  −2.544E+02A14 −4.029E+00 −2.701E+01 −2.433E+01  3.607E+01  4.009E+02 A16 0.000E+00  0.000E+00 0.000E+00 0.000E+00 −2.542E+02 7th Surface 8thSurface 9th Surface 10th Surface 11th Surface k −2.006E−01 −1.973E+011.298E+00 −3.587E+00  −5.022E+00 A4  2.222E−01  1.420E+00 8.958E−01−6.795E−01  −3.469E−01 A6 −2.504E+00 −5.214E+00 −2.087E+00  4.538E−01 2.757E−01 A8  3.378E+00  1.055E+01 2.367E+00 −1.844E−01  −2.000E−01 A10 5.730E+00 −1.626E+01 −1.743E+00  9.445E−02  1.111E−01 A12 −2.508E+01 1.668E+01 7.859E−01 −4.499E−02  −4.075E−02 A14  3.159E+01 −1.016E+01−1.805E−01  1.159E−02  8.258E−03 A16 −1.403E+01  2.658E+00 1.389E−02−1.158E−03  −6.788E−04As shown in Table 11, the imaging lens in Example 1 satisfies all theconditional expressions (1) to (8).

FIG. 2 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 1. The spherical aberration diagramshows the amount of aberration at wavelengths of F-ray (486 nm), d-ray(588 nm), and C-ray (656 nm). The astigmatism diagram shows the amountof aberration at d-ray on sagittal image surface S and the amount ofaberration at d-ray on tangential image surface T (the same is true forFIGS. 4, 6, 8, 10, 12, 14, 16, 18, and 20). As shown in FIG. 2, eachaberration is corrected properly.

In Example 1, total track length TTL is 3.25 mm, suggesting that theimaging lens is low-profile though it uses five constituent lenses.Also, the imaging lens offers a wide field of view of about 75 degreesand high brightness with an F-value of about 2.45.

Example 2

The basic lens data of Example 2 is shown in Table 2 below.

TABLE 2 Example 2 in mm f = 2.922 Fno = 2.46 ω(°) = 37.5 TTL = 3.24 ih =2.30 Surface Data Curvature Surface Refractive Abbe Surface No. i Radiusr Distance d Index Nd Number νd (Object Surface) Infinity Infinity 1(Stop) Infinity −0.165 2* 0.990 0.436 1.544 55.57 3* 31.808 0.046 4*−6.408 0.210 1.639 23.25 5* 4.855 0.306 6* −9.554 0.250 1.535 55.66 7*−16.531 0.252 8* −2.380 0.295 1.639 23.25 9* −3.300 0.080 10*  1.1700.536 1.535 55.66 11*  0.962 0.400 12  Infinity 0.175 1.517 64.20 13 Infinity 0.316 Image Plane Infinity Lens Start Surface Focal LengthConstituent Lens Data 1 2 1.869 2 4 −4.291 3 6 −42.864 4 8 −15.256 5 10−100.492 Composite Focal Length f2345 −2.480 f45  −11.266 AsphericSurface Data 2nd Surface 3rd Surface 4th Surface 5th Surface 6th Surfacek 0.000E+00  0.000E+00 −3.214E+02  5.722E+01  0.000E+00 A4 −5.668E−02 −2.078E−02 9.129E−02 2.085E−01 −2.526E−01 A6 2.535E−01 −2.019E+00−1.177E+00  8.319E−01  9.716E−02 A8 −1.805E+00   1.212E+01 1.111E+01−3.094E+00  −1.076E+01 A10 3.686E+00 −4.162E+01 −4.126E+01  1.259E+01 7.840E+01 A12 −4.291E+00   6.013E+01 6.352E+01 −3.130E+01  −2.544E+02A14 −4.355E+00  −2.592E+01 −2.292E+01  3.811E+01  3.999E+02 A160.000E+00  0.000E+00 0.000E+00 0.000E+00 −2.538E+02 7th Surface 8thSurface 9th Surface 10th Surface 11th Surface k 0.000E+00 −1.387E+014.805E+00 −3.196E+00  −4.785E+00 A4 2.616E−01  1.440E+00 8.554E−01−6.706E−01  −3.564E−01 A6 −2.462E+00  −5.210E+00 −2.044E+00  4.490E−01 2.815E−01 A8 3.400E+00  1.058E+01 2.379E+00 −1.855E−01  −1.992E−01 A105.652E+00 −1.624E+01 −1.758E+00  9.505E−02  1.107E−01 A12 −2.508E+01  1.681E+01 7.895E−01 −4.493E−02  −4.082E−02 A14 3.183E+01 −1.028E+01−1.795E−01  1.156E−02  8.227E−03 A16 −1.423E+01   2.704E+00 1.317E−02−1.160E−03  −6.671E−04As shown in Table 11, the imaging lens in Example 2 satisfies all theconditional expressions (1) to (8).

FIG. 4 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 2. As shown in FIG. 4, eachaberration is corrected properly.

In Example 2, total track length TTL is 3.24 mm, suggesting that theimaging lens is low-profile though it uses five constituent lenses.Also, the imaging lens offers a wide field of view of about 75 degreesand high brightness with an F-value of about 2.46.

Example 3

The basic lens data of Example 3 is shown in Table 3 below.

TABLE 3 Example 3 in mm f = 2.868 Fno = 2.41 ω(°) = 38.2 TTL = 3.19 ih =2.30 Surface Data Curvature Surface Refractive Abbe Surface No. i Radiusr Distance d Index Nd Number νd (Object Surface) Infinity Infinity 1(Stop) Infinity −0.165 2* 0.992 0.440 1.544 55.57 3* −99.000 0.040 4*−5.348 0.210 1.639 23.25 5* 5.129 0.302 6* −8.300 0.251 1.535 55.66 7*−14.673 0.251 8* −2.888 0.316 1.639 23.25 9* −3.545 0.048 10*  1.1700.501 1.535 55.66 11*  0.901 0.400 12  Infinity 0.175 1.517 64.20 13 Infinity 0.315 Image Plane Infinity Lens Start Surface Focal LengthConstituent Lens Data 1 2 1.809 2 4 −4.065 3 6 −36.226 4 8 −30.026 5 10−20.936 Composite Focal Length f2345 −2.336 f45  −11.156 AsphericSurface Data 2nd Surface 3rd Surface 4th Surface 5th Surface 6th Surfacek 0.000E+00 0.000E+00 −2.786E+02  5.287E+01  0.000E+00 A4 −7.374E−02 5.200E−03 1.103E−01 2.695E−01 −2.110E−01 A6 2.730E−01 −1.981E+00 −1.097E+00  8.808E−01  1.980E−02 A8 −1.783E+00  1.222E+01 1.106E+01−3.739E+00  −1.044E+01 A10 3.586E+00 −4.218E+01  −4.183E+01  1.399E+01 7.813E+01 A12 −4.291E+00  6.013E+01 6.352E+01 −3.130E+01  −2.544E+02A14 −4.355E+00  −2.592E+01  −2.292E+01  3.811E+01  3.999E+02 A160.000E+00 0.000E+00 0.000E+00 0.000E+00 −2.538E+02 7th Surface 8thSurface 9th Surface 10th Surface 11th Surface k 0.000E+00 −7.637E+00 4.099E+00 −4.803E+00  −5.518E+00 A4 1.949E−01 1.413E+00 8.432E−01−6.617E−01  −3.569E−01 A6 −2.366E+00  −5.208E+00  −2.067E+00  4.509E−01 2.811E−01 A8 3.382E+00 1.058E+01 2.390E+00 −1.868E−01  −1.986E−01 A105.673E+00 −1.629E+01  −1.756E+00  9.543E−02  1.103E−01 A12 −2.508E+01 1.683E+01 7.865E−01 −4.513E−02  −4.099E−02 A14 3.183E+01 −1.029E+01 −1.801E−01  1.161E−02  8.267E−03 A16 −1.423E+01  2.704E+00 1.317E−02−1.159E−03  −6.576E−04As shown in Table 11, the imaging lens in Example 3 satisfies all theconditional expressions (1) to (8).

FIG. 6 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 3. As shown in FIG. 6, eachaberration is corrected properly.

In Example 3, total track length TTL is 3.19 mm, suggesting that theimaging lens is low-profile though it uses five constituent lenses.Also, the imaging lens offers a wide field of view of about 76 degreesand high brightness with an F-value of about 2.41.

Example 4

The basic lens data of Example 4 is shown in Table 4 below.

TABLE 4 Example 4 in mm f = 2.924 Fno = 2.46 ω(°) = 37.5 TTL = 3.25 ih =2.30 Surface Data Curvature Surface Refractive Abbe Surface No. i Radiusr Distance d Index Nd Number νd (Object Surface) Infinity Infinity 1(Stop) Infinity −0.165 2* 0.995 0.436 1.544 55.57 3* 41.133 0.046 4*−6.090 0.210 1.639 23.25 5* 4.868 0.297 6* −22.161 0.250 1.535 55.66 7*97.647 0.260 8* −2.347 0.305 1.639 23.25 9* −3.103 0.067 10*  1.1670.540 1.535 55.66 11*  0.966 0.400 12  Infinity 0.175 1.517 64.20 13 Infinity 0.327 Image Plane Infinity Lens Start Surface Focal LengthConstituent Lens Data 1 2 1.867 2 4 −4.202 3 6 −33.749 4 8 −17.900 5 10−166.856 Composite Focal Length f2345 −2.509 f45  −13.687 AsphericSurface Data 2nd Surface 3rd Surface 4th Surface 5th Surface 6th Surfacek 0.000E+00  0.000E+00 −2.738E+02  5.747E+01  0.000E+00 A4 −5.537E−02 −1.980E−02 8.902E−02 1.962E−01 −2.985E−01 A6 2.478E−01 −2.022E+00−1.174E+00  8.527E−01  1.223E−01 A8 −1.793E+00   1.208E+01 1.112E+01−3.071E+00  −1.066E+01 A10 3.638E+00 −4.154E+01 −4.127E+01  1.244E+01 7.831E+01 A12 −4.291E+00   6.013E+01 6.352E+01 −3.130E+01  −2.544E+02A14 −4.355E+00  −2.592E+01 −2.292E+01  3.811E+01  3.999E+02 A160.000E+00  0.000E+00 0.000E+00 0.000E+00 −2.538E+02 7th Surface 8thSurface 9th Surface 10th Surface 11th Surface k 0.000E+00 −1.659E+012.876E+00 −2.903E+00  −4.835E+00 A4 2.091E−01  1.425E+00 8.654E−01−6.730E−01  −3.501E−01 A6 −2.426E+00  −5.216E+00 −2.054E+00  4.491E−01 2.793E−01 A8 3.410E+00  1.061E+01 2.376E+00 −1.855E−01  −1.994E−01 A105.613E+00 −1.625E+01 −1.755E+00  9.506E−02  1.109E−01 A12 −2.507E+01  1.675E+01 7.901E−01 −4.492E−02  −4.080E−02 A14 3.183E+01 −1.029E+01−1.797E−01  1.156E−02  8.228E−03 A16 −1.423E+01   2.762E+00 1.276E−02−1.159E−03  −6.693E−04As shown in Table 11, the imaging lens in Example 4 satisfies all theconditional expressions (1) to (8).

FIG. 8 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 4. As shown in FIG. 8, eachaberration is corrected properly.

In Example 4, total track length TTL is 3.25 mm, suggesting that theimaging lens is low-profile though it uses five constituent lenses.Also, the imaging lens offers a wide field of view of about 75 degreesand high brightness with an F-value of about 2.46.

Example 5

The basic lens data of Example 5 is shown in Table 5 below.

TABLE 5 Example 5 in mm f = 2.924 Fno = 2.46 ω(°) = 37.6 TTL = 3.25 ih =2.30 Surface Data Curvature Surface Refractive Abbe Surface No. i Radiusr Distance d Index Nd Number νd (Object Surface) Infinity Infinity 1(Stop) Infinity −0.165 2* 1.011 0.442 1.544 55.57 3* −20.764 0.048 4*−4.320 0.234 1.639 23.25 5* 5.237 0.280 6* 31.377 0.266 1.535 55.66 7*16.307 0.277 8* −2.057 0.289 1.639 23.25 9* −3.146 0.059 10*  1.0930.526 1.535 55.66 11*  0.959 0.400 12  Infinity 0.175 1.517 64.17 13 Infinity 0.314 Image Plane Infinity Lens Start Surface Focal LengthConstituent Lens Data 1 2 1.786 2 4 −3.669 3 6 −63.880 4 8 −10.371 5 1039.666 Composite Focal Length f2345 −2.271 f45  −11.351 Aspheric SurfaceData 2nd Surface 3rd Surface 4th Surface 5th Surface 6th Surface k−4.189E−02  2.986E+01 −1.209E+02  4.910E+01 −4.616E−01 A4 −5.952E−02−1.130E−02 9.437E−02 2.280E−01 −3.021E−01 A6  2.377E−01 −1.990E+00−1.087E+00  8.318E−01  1.140E−01 A8 −1.967E+00  1.229E+01 1.112E+01−3.161E+00  −1.075E+01 A10  3.870E+00 −4.197E+01 −4.137E+01  1.326E+01 7.839E+01 A12 −4.291E+00  6.014E+01 6.352E+01 −3.130E+01  −2.544E+02A14 −4.355E+00 −2.592E+01 −2.292E+01  3.811E+01  3.999E+02 A16 0.000E+00  0.000E+00 0.000E+00 0.000E+00 −2.538E+02 7th Surface 8thSurface 9th Surface 10th Surface 11th Surface k  2.145E−01 −1.964E+013.181E+00 −3.653E+00  −4.871E+00 A4  2.327E−01  1.437E+00 8.598E−01−6.750E−01  −3.481E−01 A6 −2.511E+00 −5.267E+00 −2.063E+00  4.518E−01 2.734E−01 A8  3.477E+00  1.059E+01 2.377E+00 −1.851E−01  −1.988E−01 A10 5.533E+00 −1.621E+01 −1.759E+00  9.483E−02  1.111E−01 A12 −2.508E+01 1.668E+01 7.859E−01 −4.499E−02  −4.075E−02 A14  3.183E+01 −1.028E+01−1.794E−01  1.158E−02  8.226E−03 A16 −1.423E+01  2.704E+00 1.489E−02−1.159E−03  −6.732E−04As shown in Table 11, the imaging lens in Example 5 satisfies all theconditional expressions (1) to (8).

FIG. 10 shows spherical aberration (mm), astigmatism (mm), anddistortion (%) of the imaging lens in Example 5. As shown in FIG. 10,each aberration is corrected properly.

In Example 5, total track length TTL is 3.25 mm, suggesting that theimaging lens is low-profile though it uses five constituent lenses.Also, the imaging lens offers a wide field of view of about 75 degreesand high brightness with an F-value of about 2.46.

Example 6

The basic lens data of Example 6 is shown in Table 6 below.

TABLE 6 Example 6 in mm f = 2.925 Fno = 2.44 ω(°) = 37.5 TTL = 3.26 ih =2.30 Surface Data Curvature Surface Refractive Abbe Surface No. i Radiusr Distance d Index Nd Number νd (Object Surface) Infinity Infinity 1(Stop) Infinity −0.165 2* 0.999 0.447 1.544 55.57 3* 30.714 0.040 4*−6.554 0.210 1.639 23.25 5* 5.101 0.317 6* −7.995 0.250 1.535 55.66 7*−12.724 0.260 8* −2.620 0.310 1.639 23.25 9* −4.159 0.053 10*  1.1370.534 1.535 55.66 11*  0.971 0.400 12  Infinity 0.175 1.517 64.20 13 Infinity 0.316 Image Plane Infinity Lens Start Surface Focal LengthConstituent Lens Data 1 2 1.888 2 4 −4.457 3 6 −40.969 4 8 −12.023 5 10102.339 Composite Focal Length 0 −2.537 f45  −11.256 Aspheric SurfaceData 2nd Surface 3rd Surface 4th Surface 5th Surface 6th Surface k0.000E+00  0.000E+00 −3.755E+02  6.297E+01  0.000E+00 A4 −5.586E−02 −1.468E−02 8.236E−02 2.014E−01 −2.249E−01 A6 2.632E−01 −2.013E+00−1.193E+00  8.272E−01 −6.967E−02 A8 −1.776E+00   1.207E+01 1.106E+01−3.188E+00  −1.043E+01 A10 3.751E+00 −4.162E+01 −4.155E+01  1.229E+01 7.812E+01 A12 −3.968E+00   6.010E+01 6.387E+01 −3.111E+01  −2.544E+02A14 −4.355E+00  −2.533E+01 −2.310E+01  3.811E+01  3.999E+02 A160.000E+00  0.000E+00 0.000E+00 0.000E+00 −2.538E+02 7th Surface 8thSurface 9th Surface 10th Surface 11th Surface k 0.000E+00 −2.945E+004.490E+00 −3.224E+00  −4.798E+00 A4 2.354E−01  1.493E+00 8.280E−01−6.694E−01  −3.587E−01 A6 −2.464E+00  −5.260E+00 −2.046E+00  4.487E−01 2.817E−01 A8 3.428E+00  1.060E+01 2.379E+00 −1.860E−01  −1.990E−01 A105.669E+00 −1.628E+01 −1.758E+00  9.488E−02  1.108E−01 A12 −2.508E+01  1.683E+01 7.894E−01 −4.493E−02  −4.086E−02 A14 3.182E+01 −1.030E+01−1.799E−01  1.166E−02  8.234E−03 A16 −1.415E+01   2.745E+00 1.284E−02−1.184E−03  −6.689E−04As shown in Table 11, the imaging lens in Example 6 satisfies all theconditional expressions (1) to (8).

FIG. 12 shows spherical aberration (mm), astigmatism (mm), anddistortion (%) of the imaging lens in Example 6. As shown in FIG. 12,each aberration is corrected properly.

In Example 6, total track length TTL is 3.26 mm, suggesting that theimaging lens is low-profile though it uses five constituent lenses.Also, the imaging lens offers a wide field of view of about 75 degreesand high brightness with an F-value of about 2.44.

Example 7

The basic lens data of Example 7 is shown in Table 7 below.

TABLE 7 Example 7 in mm f = 2.839 Fno = 2.41 ω(°) = 38.4 TTL = 3.19 ih =2.30 Surface Data Curvature Surface Refractive Abbe Surface No. i Radiusr Distance d Index Nd Number νd (Object Surface) Infinity Infinity 1(Stop) Infinity −0.165 2* 1.008 0.456 1.544 55.57 3* 42.064 0.033 4*−6.408 0.210 1.639 23.25 5* 4.990 0.295 6* 95.000 0.230 1.535 55.66 7*30.114 0.274 8* −1.895 0.292 1.639 23.25 9* −2.595 0.030 10*  1.0610.539 1.535 55.66 11*  0.891 0.400 12  Infinity 0.175 1.517 64.20 13 Infinity 0.314 Image Plane Infinity Lens Start Surface Focal LengthConstituent Lens Data 1 2 1.891 2 4 −4.359 3 6 −82.543 4 8 −13.117 5 10101.513 Composite Focal Length f2345 −2.648 f45  −12.218 AsphericSurface Data 2nd Surface 3rd Surface 4th Surface 5th Surface 6th Surfacek 0.000E+00  0.000E+00 −2.622E+02 5.659E+01  0.000E+00 A4 −6.806E−02 −2.978E−02  8.556E−02 1.730E−01 −2.120E−01 A6 2.877E−01 −1.972E+00−1.237E+00 8.373E−01 −2.195E−01 A8 −1.768E+00   1.209E+01  1.113E+01−2.953E+00  −1.012E+01 A10 3.860E+00 −4.190E+01 −4.195E+01 1.080E+01 7.791E+01 A12 −4.148E+00   5.998E+01  6.417E+01 −2.938E+01  −2.544E+02A14 −4.355E+00  −2.499E+01 −2.377E+01 3.811E+01  3.999E+02 A16 0.000E+00 0.000E+00  0.000E+00 0.000E+00 −2.538E+02 7th Surface 8th Surface 9thSurface 10th Surface 11th Surface k 0.000E+00 −2.011E+01 −6.981E+00−4.876E+00  −5.237E+00 A4 2.142E−01  1.480E+00  8.858E−01 −6.458E−01 −3.403E−01 A6 −2.396E+00  −5.356E+00 −2.096E+00 4.483E−01  2.730E−01 A83.280E+00  1.081E+01  2.373E+00 −1.879E−01  −1.995E−01 A10 5.637E+00−1.631E+01 −1.750E+00 9.458E−02  1.113E−01 A12 −2.494E+01   1.661E+01 7.937E−01 −4.484E−02  −4.106E−02 A14 3.177E+01 −1.047E+01 −1.777E−011.173E−02  8.246E−03 A16 −1.401E+01   3.062E+00  1.058E−02 −1.197E−03 −6.594E−04As shown in Table 11, the imaging lens in Example 7 satisfies all theconditional expressions (1) to (8).

FIG. 14 shows spherical aberration (mm), astigmatism (mm), anddistortion (%) of the imaging lens in Example 7. As shown in FIG. 14,each aberration is corrected properly.

In Example 7, total track length TTL is 3.19 mm, suggesting that theimaging lens is low-profile though it uses five constituent lenses.Also, the imaging lens offers a wide field of view of about 77 degreesand high brightness with an F-value of about 2.41.

Example 8

The basic lens data of Example 8 is shown in Table 8 below.

TABLE 8 Example 8 in mm f = 2.949 Fno = 2.43 ω(°) = 37.3 TTL = 3.29 ih =2.30 Surface Data Curvature Surface Refractive Abbe Surface No. i Radiusr Distance d Index Nd Number νd (Object Surface) Infinity Infinity 1(Stop) Infinity −0.165 2* 1.018 0.438 1.544 55.57 3* 5.930 0.031 4*95.000 0.210 1.635 23.97 5* 4.866 0.318 6* −5.968 0.250 1.614 25.58 7*−8.677 0.246 8* −3.085 0.278 1.614 25.58 9* −6.702 0.095 10*  1.2400.585 1.535 55.66 11*  1.102 0.400 12  Infinity 0.175 1.517 64.20 13 Infinity 0.322 Image Plane Infinity Lens Start Surface Focal LengthConstituent Lens Data 1 2 2.192 2 4 −8.085 3 6 −32.255 4 8 −9.589 5 1038.613 Composite Focal Length f2345 −3.490 f45  −10.359 Aspheric SurfaceData 2nd Surface 3rd Surface 4th Surface 5th Surface 6th Surface k0.000E+00 0.000E+00 0.000E+00 5.627E+01  0.000E+00 A4 −4.969E−02 −7.269E−02  9.271E−02 1.289E−01 −1.513E−01 A6 2.309E−01 −2.043E+00 −1.213E+00  8.378E−01 −7.550E−02 A8 −1.870E+00  1.197E+01 1.095E+01−2.463E+00  −1.040E+01 A10 4.287E+00 −4.139E+01  −4.177E+01  1.023E+01 7.846E+01 A12 −4.180E+00  6.007E+01 6.389E+01 −3.111E+01  −2.544E+02A14 −4.355E+00  −2.533E+01  −2.310E+01  3.811E+01  3.999E+02 A160.000E+00 0.000E+00 0.000E+00 0.000E+00 −2.538E+02 7th Surface 8thSurface 9th Surface 10th Surface 11th Surface k 0.000E+00 3.318E−011.673E+01 −2.337E+00  −4.193E+00 A4 2.557E−01 1.474E+00 7.663E−01−6.643E−01  −3.499E−01 A6 −2.342E+00  −5.303E+00  −2.023E+00  4.459E−01 2.763E−01 A8 3.369E+00 1.066E+01 2.397E+00 −1.871E−01  −1.983E−01 A105.580E+00 −1.642E+01  −1.747E+00  9.453E−02  1.107E−01 A12 −2.491E+01 1.740E+01 7.842E−01 −4.483E−02  −4.099E−02 A14 3.181E+01 −1.098E+01 −1.833E−01  1.170E−02  8.271E−03 A16 −1.420E+01  2.962E+00 1.274E−02−1.185E−03  −6.698E−04As shown in Table 11, the imaging lens in Example 8 satisfies all theconditional expressions (1) to (8).

FIG. 16 shows spherical aberration (mm), astigmatism (mm), anddistortion (%) of the imaging lens in Example 8. As shown in FIG. 16,each aberration is corrected properly.

In Example 8, total track length TTL is 3.29 mm, suggesting that theimaging lens is low-profile though it uses five constituent lenses.Also, the imaging lens offers a wide field of view of about 75 degreesand high brightness with an F-value of about 2.43.

Example 9

The basic lens data of Example 9 is shown in Table 9 below.

TABLE 9 Example 9 in mm f = 2.921 Fno = 2.43 ω(°) = 37.6 TTL = 3.25 ih =2.30 Surface Data Curvature Surface Refractive Abbe Surface No. i Radiusr Distance d Index Nd Number νd (Object Surface) Infinity Infinity 1(Stop) Infinity −0.165 2* 1.010 0.461 1.544 55.57 3* −82.593 0.031 4*−5.660 0.210 1.639 23.25 5* 5.131 0.329 6* −5.149 0.250 1.535 55.66 7*−7.912 0.243 8* −3.358 0.327 1.535 55.66 9* −6.597 0.047 10*  1.1490.526 1.535 55.66 11*  0.986 0.400 12  Infinity 0.175 1.517 64.20 13 Infinity 0.314 Image Plane Lens Start Surface Focal Length ConstituentLens Data 1 2 1.838 2 4 −4.180 3 6 −28.471 4 8 −13.251 5 10 101.448Composite Focal Length f2345 −2.402 f45  −12.616 Aspheric Surface Data2nd Surface 3rd Surface 4th Surface 5th Surface 6th Surface k 0.000E+000.000E+00 −2.002E+02  6.289E+01  0.000E+00 A4 −5.363E−02  −1.045E−03 1.061E−01 2.046E−01 −1.950E−01 A6 2.613E−01 −1.957E+00  −1.216E+00 7.893E−01 −1.227E−01 A8 −1.770E+00  1.196E+01 1.097E+01 −3.162E+00 −1.036E+01 A10 3.979E+00 −4.169E+01  −4.178E+01  1.193E+01  7.827E+01A12 −4.181E+00  6.007E+01 6.389E+01 −3.111E+01  −2.544E+02 A14−4.355E+00  −2.533E+01  −2.310E+01  3.811E+01  3.999E+02 A16 0.000E+000.000E+00 0.000E+00 0.000E+00 −2.538E+02 7th Surface 8th Surface 9thSurface 10th Surface 11th Surface k 0.000E+00 8.600E−01 1.033E+01−2.599E+00  −4.593E+00 A4 2.149E−01 1.481E+00 8.100E−01 −6.781E−01 −3.599E−01 A6 −2.431E+00  −5.268E+00  −2.042E+00  4.470E−01  2.813E−01A8 3.475E+00 1.055E+01 2.374E+00 −1.859E−01  −1.979E−01 A10 5.703E+00−1.631E+01  −1.753E+00  9.474E−02  1.106E−01 A12 −2.509E+01  1.739E+017.904E−01 −4.493E−02  −4.088E−02 A14 3.181E+01 −1.098E+01  −1.816E−01 1.167E−02  8.230E−03 A16 −1.418E+01  2.960E+00 1.241E−02 −1.181E−03 −6.694E−04As shown in Table 11, the imaging lens in Example 9 satisfies all theconditional expressions (1) to (8).

FIG. 18 shows spherical aberration (mm), astigmatism (mm), anddistortion (%) of the imaging lens in Example 9. As shown in FIG. 18,each aberration is corrected properly.

In Example 9, total track length TTL is 3.25 mm, suggesting that theimaging lens is low-profile though it uses five constituent lenses.Also, the imaging lens offers a wide field of view of about 75 degreesand high brightness with an F-value of about 2.43.

Example 10

The basic lens data of Example 10 is shown in Table 10 below.

TABLE 10 Example 10 in mm f = 2.760 Fno = 2.41 ω(°) = 39.7 TTL = 3.09 ih= 2.30 Surface Data Curvature Surface Refractive Abbe Surface No. iRadius r Distance d Index Nd Number νd (Object Surface) InfinityInfinity 1 (Stop) Infinity −0.165 2* 0.979 0.413 1.544 55.57 3* 4.5150.047 4* 89.131 0.210 1.639 23.25 5* 5.241 0.283 6* −7.535 0.229 1.53555.66 7* −8.543 0.251 8* −3.233 0.294 1.639 23.25 9* −6.318 0.042 10* 1.086 0.509 1.535 55.66 11*  0.921 0.400 12  Infinity 0.175 1.517 64.2013  Infinity 0.301 Image Plane Lens Start Surface Focal LengthConstituent Lens Data 1 2 2.208 2 4 −8.721 3 6 −129.665 4 8 −10.759 5 10146.606 Composite Focal Length f2345 −3.918 f45  −9.638 Aspheric SurfaceData 2nd Surface 3rd Surface 4th Surface 5th Surface 6th Surface k0.000E+00 0.000E+00 0.000E+00 6.491E+01  0.000E+00 A4 −5.668E−02 −5.900E−02  9.466E−02 1.534E−01 −9.712E−02 A6 2.506E−01 −2.017E+00 −1.298E+00  9.612E−01 −1.139E−01 A8 −1.677E+00  1.190E+01 1.114E+01−3.229E+00  −9.826E+00 A10 3.666E+00 −4.127E+01  −4.131E+01  1.254E+01 7.730E+01 A12 −3.994E+00  6.008E+01 6.393E+01 −3.088E+01  −2.544E+02A14 −4.355E+00  −2.517E+01  −2.337E+01  3.811E+01  3.999E+02 A160.000E+00 0.000E+00 0.000E+00 0.000E+00 −2.538E+02 7th Surface 8thSurface 9th Surface 10th Surface 11th Surface k 0.000E+00 4.746E+004.971E+00 −5.024E+00  −4.953E+00 A4 2.123E−01 1.433E+00 7.690E−01−6.513E−01  −3.747E−01 A6 −2.230E+00  −5.232E+00  −2.033E+00  4.468E−01 2.907E−01 A8 3.500E+00 1.070E+01 2.392E+00 −1.870E−01  −2.000E−01 A105.491E+00 −1.633E+01  −1.755E+00  9.469E−02  1.102E−01 A12 −2.517E+01 1.682E+01 7.871E−01 −4.499E−02  −4.109E−02 A14 3.184E+01 −1.031E+01 −1.814E−01  1.166E−02  8.269E−03 A16 −1.412E+01  2.798E+00 1.264E−02−1.163E−03  −6.533E−04As shown in Table 11, the imaging lens in Example 10 satisfies all theconditional expressions (1) to (8).

FIG. 20 shows spherical aberration (mm), astigmatism (mm), anddistortion (%) of the imaging lens in Example 10. As shown in FIG. 20,each aberration is corrected properly.

In Example 10, total track length TTL is 3.09 mm, suggesting that theimaging lens is low-profile though it uses five constituent lenses.Also, the imaging lens offers a wide field of view of about 79 degreesand high brightness with an F-value of about 2.41.

TABLE 11 Example Example 1 Example 2 Example 3 Example 4 Example 5Example 6 Example 7 Example 8 Example 9 10 Conditional Expression (1)0.71 0.71 0.69 0.71 0.71 0.71 0.69 0.72 0.71 0.67 TTL/2ih ConditionalExpression (2) 32.32 32.32 32.32 32.32 32.32 32.32 32.32 31.60 32.3232.32 vd1 − vd2 Conditional Expression (3) 32.41 32.41 32.41 32.41 32.4132.41 32.41 0.00 0.00 32.41 vd3 − vd4 Conditional Expression (4) 0.600.64 0.63 0.64 0.61 0.65 0.67 0.74 0.63 0.80 f1/f Conditional Expression(5) −0.76 −0.85 −0.81 −0.86 −0.78 −0.87 −0.93 −1.18 −0.82 −1.42 f2345/fConditional Expression (6) 1.67 1.66 1.79 1.66 1.79 1.74 1.76 1.65 1.761.90 r4/f Conditional Expression (7) −0.86 −1.06 −0.98 −1.05 −0.91 −1.07−1.05 −1.41 −0.98 −1.55 (r1 + r2)/(r1 − r2) Conditional Expression (8)−3.99 −3.86 −3.89 −4.68 −3.88 −3.85 −4.30 −3.51 −4.32 −3.49 f45/f

As explained above, the imaging lenses according to the examples of thepresent invention are low-profile enough to meet the growing demand forlow-profileness, with total track length TTL of 3.3 mm or less and atotal length to diagonal ratio of 0.8 or less, though they use fiveconstituent lenses. In addition, these imaging lenses can offer a wideimaging field of view of 75 to 79 degrees and high brightness with anF-value of 2.5 or less, correct various aberrations properly and featurelow cost.

When any one of the imaging lenses composed of five constituent lensesaccording to the examples of the present invention is used for anoptical system built in an image pickup device mounted in anincreasingly compact and low-profile mobile terminal such as asmartphone, mobile phone or PDA (Personal Digital Assistant), or a gameconsole or an information terminal such as a PC, or a home appliancewith a camera function, it delivers high camera performance andcontributes to the low-profileness of the image pickup device.

The effects of the present invention are as follows.

According to the present invention, there is provided a compact imaginglens which meets the demand for low-profileness, offers high brightnesswith an F-value of 2.5 or less and a wide field of view and correctsvarious aberrations properly.

What is claimed is:
 1. An imaging lens which forms an image of an objecton a solid-state image sensor, comprising, in order from an object sideto an image side of the imaging lens: a first lens that is a meniscuslens having a convex surface facing the object side; a second lens; athird lens that is a meniscus lens and has a convex surface that facesthe image side and intersects an optical axis of the imaging lens; afourth lens having a concave surface facing the object side and a convexsurface that faces the image side and intersects the optical axis; and afifth lens; wherein an F-value is 2.5 or less, and conditionalexpressions (4b) and (6b) below are satisfied:0.6≤f1/f≤0.8  (4b)1.65≤r4/f≤1.9  (6b) where f: overall focal length of the imaging lens,f1: focal length of the first lens, and r4: curvature radius of animage-side surface of the second lens.
 2. The imaging lens according toclaim 1, wherein the first lens has positive refractive power, theimage-side surface of the second lens is concave, and the second lenshas negative refractive power.
 3. The imaging lens according to claim 1,wherein the fourth lens has aspheric surfaces facing both sides, thefifth lens has a concave surface facing the image side and asphericsurfaces facing both sides, and the aspheric surface facing the imageside of the fifth lens has a pole-change point separated from theoptical axis.
 4. The imaging lens according to claim 1, whereinconditional expressions (1) and (2) below are satisfied:TTL/2ih≤0.8  (1)20<νd1−νd2<50  (2) where TTL: total track length, ih: maximum imageheight, νd1: Abbe number of the first lens at d-ray, and νd2: Abbenumber of the second lens at d-ray.
 5. The imaging lens according toclaim 1, wherein a conditional expression (3) below is satisfied:0<νd3−νd4<40  (3) where νd3: Abbe number of the third lens at d-ray, andνd4: Abbe number of the fourth lens at d-ray.
 6. The imaging lensaccording to claim 1, wherein a conditional expression (5) below issatisfied:−1.5<f2345/f<−0.6  (5) where f2345: composite focal length of the secondlens, the third lens, the fourth lens, and the fifth lens.
 7. Theimaging lens according to claim 1, wherein a conditional expression (7)below is satisfied:−1.9<(r1+r2)/(r1−r2)<−0.7  (7) where r1: curvature radius of anobject-side surface of the first lens, and r2: curvature radius of animage-side surface of the first lens.
 8. The imaging lens according toclaim 1, wherein a conditional expression (8) below is satisfied:−6.0<f45/f<−3.0  (8) where f45: composite focal length of the fourthlens and the fifth lens.
 9. An imaging lens which forms an image of anobject on a solid-state image sensor, comprising, in order from anobject side to an image side of the imaging lens: a first lens having aconvex surface facing the image side; a second lens having a concavesurface facing the image side; a third lens having a concave surfacefacing the image side and negative refractive power; a fourth lens; anda fifth lens having a convex surface that faces the object side andintersects an optical axis of the imaging lens; wherein an F-value is2.5 or less, and conditional expressions (3) and (8b) below aresatisfied:0<νd3−νd4<40  (3)−4.68≤f45/f≤−3.49  (8b) where νd3: Abbe number of the third lens atd-ray, νd4: Abbe number of the fourth lens at d-ray, f: overall focallength of the imaging lens, and f45: composite focal length of thefourth lens and the fifth lens.
 10. The imaging lens according to claim9, wherein the first lens has a convex surface facing the object sideand positive refractive power, and the second lens has negativerefractive power.
 11. The imaging lens according to claim 9, wherein thefourth lens is a meniscus lens having a convex surface facing the imageside and aspheric surfaces facing both sides, the fifth lens has aconcave surface facing the image side and aspheric surfaces facing bothsides, and the aspheric surface facing the image side of the fifth lenshas a pole-change point separated from the optical axis.
 12. The imaginglens according to claim 9, wherein conditional expressions (1) and (2)below are satisfied:TTL/2ih≤0.8  (1)20<νd1−νd2<50  (2) where TTL: total track length, ih: maximum imageheight, νd1: Abbe number of the first lens at d-ray, and νd2: Abbenumber of the second lens at d-ray.
 13. The imaging lens according toclaim 9, wherein conditional expressions (4) and (5) below aresatisfied:0.4<f1/f<1.0  (4)−1.5<f2345/f<−0.6  (5) where f1: focal length of the first lens, andf2345: composite focal length of the second lens, the third lens, thefourth lens, and the fifth lens.
 14. The imaging lens according to claim9, wherein a conditional expression (6) below is satisfied:1.5<r4/f<2.3  (6) where r4: curvature radius of an image-side surface ofthe second lens.
 15. The imaging lens according to claim 9, wherein aconditional expression (7) below is satisfied:−1.9<(r1+r2)/(r1−r2)<−0.7  (7) where r1: curvature radius of anobject-side surface of the first lens, and r2: curvature radius of animage-side surface of the first lens.
 16. An imaging lens which forms animage of an object on a solid-state image sensor, comprising, in orderfrom an object side to an image side of the imaging lens: a first lenshaving a convex surface facing the image side; a second lens having aconcave surface facing the image side; a third lens having a concavesurface facing the image side and negative refractive power; a fourthlens; and a fifth lens that is a meniscus lens; wherein an F-value is2.5 or less, and conditional expressions (3), (5b), and (8b) below aresatisfied:0<νd3−νd4<40  (3)−1.42≤f2345/f≤−0.76  (5b)−4.68≤f45/f≤−3.49  (8b) where νd3: Abbe number of the third lens atd-ray, νd4: Abbe number of the fourth lens at d-ray, f: overall focallength of the imaging lens, f2345: composite focal length of the secondlens, the third lens, the fourth lens, and the fifth lens, and f45:composite focal length of the fourth lens and the fifth lens.
 17. Theimaging lens according to claim 16, wherein the first lens has a convexsurface facing the object side and positive refractive power, and thesecond lens has negative refractive power.
 18. The imaging lensaccording to claim 16, wherein the fourth lens is a meniscus lens havinga convex surface facing the image side and aspheric surfaces facing bothsides, the fifth lens has a concave surface facing the image side andaspheric surfaces facing both sides, and the aspheric surface facing theimage side of the fifth lens has a pole-change point separated from anoptical axis of the imaging lens.
 19. The imaging lens according toclaim 16, wherein conditional expressions (1) and (2) below aresatisfied:TTL/2ih≤0.8  (1)20<νd1−νd2<50  (2) where TTL: total track length, ih: maximum imageheight, νd1: Abbe number of the first lens at d-ray, and νd2: Abbenumber of the second lens at d-ray.
 20. The imaging lens according toclaim 16, wherein a conditional expression (4) below is satisfied:0.4<f1/f<1.0  (4) where f1: focal length of the first lens.
 21. Theimaging lens according to claim 16, wherein a conditional expression (6)below is satisfied:1.5<r4/f<2.3  (6) where r4: curvature radius of an image-side surface ofthe second lens.
 22. The imaging lens according to claim 16, wherein aconditional expression (7) below is satisfied:−1.9<(r1+r2)/(r1−r2)<−0.7  (7) where r1: curvature radius of anobject-side surface of the first lens r2: curvature radius of animage-side surface of the first lens.